Although conventional fireplaces are intended to produce heat within the rooms within which they are located, their heating capabilities are often unsatisfactory and as a result it is desirable to increase their heating efficiency by situating a heat exchanger within the fireplace. Several problems generally arise when conventional heat exchangers are so situated. One problem is that many of these heat exchangers do not utilize the natural convection of heated air in conducting such air through a fireplace and returning it to the room in which the fireplace is located. Another problem is that most of these heat exchangers do not return heated air to the room at an elevated level but instead return it along the floor where it has little utility in heating the room. Yet another problem is that most heat exchangers are self-contained units which do not cooperate with existing heatalator or heat form structure in order to enhance the heating efficiency of such structure. Still another problem is that many elements of the heat exchangers wear out or burn out and cannot be replaced, or replaced only with great difficulty. Furthermore, conventional heat exchangers are large and unattractive, detracting from the appearance of both the fireplace and the room in which they are situated.
The above-noted problems have remained generally unsolved by the prior art. Slate, U.S. Pat. No. 4,122,825, discloses a fireplace air heater for returning warm air to an adjacent room. A blower unit aids in withdrawing cool air from the room and such cool air is passed through a number of cool air conduits to a warm air manifold. An ash screen and a removable ash pan are positioned below the heater. This device is self-contained, returning heated air along the floor where it is initially received, and it is incapable of being used with an existing heat form or heatalator and therefore does not utilize the convection of heated air to maximum advantage.
Young et al., U.S. Pat. No. 4,078,542, discloses a heat transfer system which includes a plurality of cylindrical conduits for returning heated air to an adjacent room. A blower supplies room air to the conduits and a metal grate receives ashes and coals and can be removed for cleaning. The conduits are not slanted to take advantage of hot air convection and the system is self-contained, therefore being incapable of use with an existing heat form or heatalator.
Eggley, U.S. Pat. No. 4,010,729, discloses a heat exchanger unit comprising a grate which conducts room air adjacent to a fire and through an exhaust transfer duct into an adjacent room. This unit relies upon a blower to propel room air through the system rather than convection currents and it is not designed to be attached to a heat form or heatalator to enhance the heating efficiency of the existing fireplace structure.
The heat exchanger of Englert, U.S. Pat. No. 3,635,211, comprises a generally U-shaped structure which returns heated room air to an adjacent room. Not only is this device large and unattractive, but it cannot be coupled with existing heatalator or heat form structures in order to render them more heat efficient.
Leibst, U.S. Pat. No. 2,702,030, discloses a heat exchanger comprising a plurality of bars which conduct room air into an existing fireplace heating chamber which in turn conducts the heated air into an adjacent room. This device includes an ashtray to receive spent fire wood and coal which falls between the bars. Although this device is coordinated with existing fireplace structure, it does not provide for slanting the tubes to take advantage of the convection of room air as it is heated nor is it self-contained by a frame structure which both houses the tubes and is securely attached to the fireplace.
While all these prior art devices are designed to improve the heat efficiency of a conventional fireplace, none of them are able to simply and inexpensively overcome all of the aforementioned problems. None of these heat exchangers comprises an attractive unit which both utilizes hot air convection by angling the cool air transport tubes through a fireplace fire and cooperates with existing heatalator or heat form structure to render a conventional fireplace more heat efficient. Nor do any of these devices include frame structure which is securely attached to a fireplace rear wall and which retains the transport tubes so that they can be easily replaced. It is apparent that none of these prior art devices overcome all of the noted problems. The present invention fills such a need.